A shared suffix does not make a shared experiment
Semax, Selank and DSIP are often grouped together. Their origins and their strongest findings point in different directions.
Molecular lineage
Semax and Selank are both synthetic heptapeptides with a Pro-Gly-Pro tail intended to slow enzymatic breakdown. Their parent fragments are different: ACTH for Semax, tuftsin for Selank. DSIP began as an isolated nonapeptide and has an unresolved receptor story.
I’m wary of giving these compounds the same job simply because they share a page in a discussion of brain health. The family resemblance helps compare experiments while leaving treatment rankings unsupported.
| Compound | The change | The question that remains |
|---|---|---|
| Semax | ACTH fragment extended with Pro-Gly-Pro | Does the injury-model signal translate to a repeatable human benefit? |
| Selank | Tuftsin extended with Pro-Gly-Pro | How do the nervous-system and immune effects fit together in people? |
| DSIP | The newer fusion work alters native DSIP | Which findings concern the original peptide, and which concern the redesign? |
Comparative evidence
For Semax, the regional neurotrophin changes in rats and immune and vascular gene shifts after rat brain ischemia make a substantial mechanistic story. They do not test concentration in healthy humans.
For Selank, the GABA-binding review connects the anxiety hypothesis to laboratory observations, while the cytokine study in diagnosed patients brings an immune finding into humans. It does not make every proposed anxiety or cognitive benefit a clinical result.
For DSIP, the six-person sleep pilot is directly human but small and old. The newer mouse experiment is more recent but tests a fusion peptide. Recency and human relevance have moved in different directions.
Those mismatches are the comparison, to my mind. A score for best peptide would conceal them.
Uncertainties for Semax, Selank and DSIP
Semax’s brief intact residence in rats does not explain the duration of every community account. Selank’s many-system activity does not establish safe combinations. DSIP’s newer analog work does not supply the missing receptor or a modern human safety trial for native DSIP.
The community reports also overlap: clarity, calm and better-feeling sleep, alongside non-response and adverse experiences. They are anecdotes, not clinical evidence. Their familiar vocabulary cannot turn distinct experiments into a common treatment category.
I’d count progress differently for each compound. Semax needs a convincing bridge from injury models to the human claim being made; Selank needs human work that accounts for its immune as well as nervous-system effects; DSIP needs the tested molecule named plainly and the original sleep claim tested reproducibly.
Regulatory status
None of the three is FDA- or EMA-approved. Semax and Selank have Russian prescription-drug registration, with Semax also registered in Ukraine. DSIP has no approved drug product. In the United States, individual clinical prescribing decisions and research-labelled supply remain distinct channels.
FDA’s page lists Semax, Selank and emideltide (DSIP) in the nominated-but-withdrawn table, with safety concerns still recorded. Withdrawn nominations do not authorize compounding or place these substances in Category 1. Compounded medicines are not FDA-approved.
The current regulatory entry describes status and gives no date for an FDA move. Nor does conditional prescribing settle a question about efficacy, long-term safety or the identity and purity of research-labelled material.